This invention relates to application of hot melt adhesives and, more particularly, to a connector for connecting a hot melt applicator to a remote source of electrical power for operating the applicator.
Thermoplastic adhesives or so-called "hot melt" adhesives are now widely used to secure substrates together in a great variety of applications. These hot melt materials are essentially solvent free adhesives which are applied in a molten state and form a bond upon cooling to a solid state. By reason of their quick setting characteristics, their adhesive "tack" and their gap filling properties, they are used in many industrial adhesive applications. For example, such adhesives are now commonly used in the assembly and manufacture of automobiles, furniture, aircraft subassemblies and the like. Many of these assembly operations use production line techniques wherein the adhesive applicator must be moved by an operator to and around the assembly part during application of the adhesive to the substrate. In such applications the adhesive is quite commonly applied to the substrate by an adhesive handgun to which the molten adhesive is supplied through a flexible hose. In this type of system, the molten feedstock or molten adhesive is converted from a solid state, e.g., pellets, bulk or chunks, to a molten state by a melter structure such as an electrically heated melting tank remote from the applicator. The molten feedstock is pumped from the melting tank to the gun or dispenser through a feed hose which is heated to a temperature on the order of 350.degree. F. to prevent the molten feedstock from solidifying in the hose as it travels between the melting tank and the applicator. This hose is connected at its end remote from the melting tank to the applicator such that the molten adhesive is delivered to the gun. The gun has an on and off actuation so that the material may be applied as the operator determines.
Since it is necessary for the hot melt adhesive to stay in its molten condition until applied to the substrate, the applicator or gun itself contains a heater as well as a temperature controller in the gun. The heater and temperature controller are typically electrically operated and thus the gun requires the delivery of electrical power to it.
A thermally insulated electrically heated hose for transmitting hot melt adhesive to an applicator is disclosed in U.S. Pat. No. 4,455,474, assigned to the assignee of this invention. That hose as disclosed includes two pair of electrical wires which run along the length of the hose as well as one ground wire. These electrical wires are connected at the end of the hose close to the melting tank to a source of electric power. At the opposite end or end remote from the source of adhesive material and power, the wires extend radially from the side of the hose. A connector for connecting these wires to the applicator is also disclosed comprising a cuff fitting over the end of the hose having a hole or aperture in its side through which the electrical leads pass and a plastic block which is mounted to a boss surrounding the aperture by conventional screws. The electrical leads are drawn up through the aperture and inserted in one end of a conventional electrical plug. The wires are then pushed back into the block and aperture and the plug secured in the block by means of another screw. That block then receives the a plug connection of electrical leads from the gun.